<!DOCTYPE html>
<style>
#div-horizontal {
  width: 200px;
  height: 100px;
  background-color: green;
}

#div-vertical {
  width: 100px;
  height: 200px;
  background-color: green;
}
</style>

<script src="resources/srcset-helper.js"></script>

<div id="div-horizontal"></div>
<br>
<div id="div-vertical"></div>

